"""
MCP 服务器
实现 MCP 协议的服务器端功能
"""

import asyncio
import json
import logging
from typing import Dict, List, Optional

from fastapi import FastAPI, HTTPException, Request
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel

from ..client.protocol import MCPRequest, MCPResponse, MCPSerializer
from ..client.security import MCPSecurity

class MCPServer:
    """MCP 服务器
    
    提供 MCP 协议的服务器端实现:
    - 请求处理和路由
    - 会话管理
    - 安全控制
    - 状态监控
    """
    
    def __init__(self, config: Dict):
        """初始化服务器
        
        Args:
            config: 服务器配置
                host: 主机地址
                port: 端口
                security: 安全配置
                cors_origins: CORS 允许的源
        """
        self.config = config
        self.logger = logging.getLogger(__name__)
        
        # 初始化 FastAPI 应用
        self.app = FastAPI(title="MCP Server")
        
        # 配置 CORS
        self.app.add_middleware(
            CORSMiddleware,
            allow_origins=config.get("cors_origins", ["*"]),
            allow_credentials=True,
            allow_methods=["*"],
            allow_headers=["*"],
        )
        
        # 初始化安全管理器
        self.security = MCPSecurity(config["security"])
        
        # 初始化序列化器
        self.serializer = MCPSerializer()
        
        # 注册路由
        self._register_routes()
        
        # 活跃会话
        self.active_sessions: Dict[str, Dict] = {}
        
        # 服务器状态
        self.status = {
            "start_time": None,
            "request_count": 0,
            "error_count": 0,
            "active_sessions": 0
        }
        
    def _register_routes(self):
        """注册 API 路由"""
        
        @self.app.post("/mcp/connect")
        async def connect(request: Request):
            """建立 MCP 连接"""
            try:
                body = await request.json()
                client_id = body.get("client_id")
                scopes = body.get("scopes", [])
                
                # 生成访问令牌
                token = self.security.generate_token(client_id, scopes)
                
                # 创建会话
                session_id = f"session_{len(self.active_sessions) + 1}"
                self.active_sessions[session_id] = {
                    "client_id": client_id,
                    "token": token,
                    "scopes": scopes,
                    "created_at": asyncio.get_event_loop().time()
                }
                
                self.status["active_sessions"] = len(self.active_sessions)
                
                return {
                    "session_id": session_id,
                    "token": token
                }
                
            except Exception as e:
                self.logger.error(f"Connection error: {e}")
                self.status["error_count"] += 1
                raise HTTPException(status_code=400, detail=str(e))
                
        @self.app.post("/mcp/request")
        async def handle_request(request: Request):
            """处理 MCP 请求"""
            try:
                # 验证令牌
                token = request.headers.get("Authorization")
                if not token:
                    raise HTTPException(status_code=401, detail="Missing token")
                    
                token = token.replace("Bearer ", "")
                valid, payload = self.security.validate_token(token)
                if not valid:
                    raise HTTPException(status_code=401, detail="Invalid token")
                    
                # 解析请求
                body = await request.json()
                mcp_request = self.serializer.deserialize_request(body)
                
                # 验证权限
                if not self.security.check_permission(payload, mcp_request.required_scopes):
                    raise HTTPException(status_code=403, detail="Insufficient permissions")
                    
                # 处理请求
                response = await self._process_request(mcp_request)
                
                # 更新状态
                self.status["request_count"] += 1
                
                return self.serializer.serialize_response(response)
                
            except Exception as e:
                self.logger.error(f"Request error: {e}")
                self.status["error_count"] += 1
                raise HTTPException(status_code=400, detail=str(e))
                
        @self.app.post("/mcp/disconnect")
        async def disconnect(request: Request):
            """断开 MCP 连接"""
            try:
                body = await request.json()
                session_id = body.get("session_id")
                
                if session_id in self.active_sessions:
                    del self.active_sessions[session_id]
                    self.status["active_sessions"] = len(self.active_sessions)
                    
                return {"status": "disconnected"}
                
            except Exception as e:
                self.logger.error(f"Disconnection error: {e}")
                self.status["error_count"] += 1
                raise HTTPException(status_code=400, detail=str(e))
                
        @self.app.get("/mcp/status")
        async def get_status():
            """获取服务器状态"""
            return self.status
            
    async def _process_request(self, request: MCPRequest) -> MCPResponse:
        """处理 MCP 请求
        
        Args:
            request: MCP 请求
            
        Returns:
            MCPResponse: MCP 响应
        """
        # TODO: 实现具体的请求处理逻辑
        # 这里需要根据请求类型调用相应的处理器
        
        response = MCPResponse(
            request_id=request.request_id,
            status="success",
            data={"message": "Request processed"}
        )
        
        return response
        
    async def start(self):
        """启动服务器"""
        self.status["start_time"] = asyncio.get_event_loop().time()
        self.logger.info(f"MCP Server starting on {self.config['host']}:{self.config['port']}")
        
        # 启动 FastAPI 应用
        import uvicorn
        await uvicorn.run(
            self.app,
            host=self.config["host"],
            port=self.config["port"]
        )
        
    async def stop(self):
        """停止服务器"""
        # 清理活跃会话
        self.active_sessions.clear()
        self.status["active_sessions"] = 0
        
        self.logger.info("MCP Server stopped") 